This question already has an answer here:
The stack exchange sites chose a unique approach regarding who can post answers vs. who can post comments. This occasionally leads to anonymous / low-rep users leaving answers-which-should-have-been-comments simply because adding answers is easy and accessible while adding comments is unexplained on a question page.
I propose to make it clearer to anonymous and low-rep users visiting just the question page that commenting is only available to registered and higher-rep users.
I'm not quite sure how this could be done; I guess it's a good question for the UX SE site. A couple of ideas I've thought about:
- Make the "add comment" visible to these users, but make clicking it show a friendly "you have to be registered and with over X rep to add a comment" message.
- Add a grey "you must be registered and have over X rep to comment on this answer" line in the comment area of each answer.
Optionally, make one of the above visible only when the user hovers over the question/answer area, in a similar way to how the "useful for me" link is displayed.